I realised that one piece of my response to
@trade4succes wasn't put particularly well and needs unpacking a bit as the directional swing trades can employ different strategies/structures.
The OtM Credit and Debit spreads are more dependent on theta decay, and less dependent on the IV falling for legs relatively close together.
The AtM/ItM Debit spreads and the AtM/OtM Credit spreads both utilise a short 50-delta leg, so benefit to a significantly greater extent on the reduction of IV to close in profit.
Obviously in the case of the Debits, the combination of increasing delta of the long leg (and intrinsic value in the spread) with reduction of IV of the short leg (and extrinsic value in the spread) (are expected to) work together to provide what I consider to be pretty good returns.
In the case of the Credit spreads, reduction of IV of the short leg (and extrinsic value in the spread) with theta decay on both are driving returns.
Hope this helps.